Welcome to the forum @Shaun0572
Please create a simple flow using Inject nodes to simulate your inputs, and your Join and Function nodes. Export those nodes and post the flow here using the technique described below. Then we can see what you are doing and suggest improvements.
In order to make code readable and usable it is necessary to surround your code with three backticks (also known as a left quote or backquote ```)
```
code goes here
```
See this post for more details - How to share code or flow json
